Abstract
The western region of Saudi Arabia is a major vegetation diversity hotspot with wide range of habitats and variant climatic and topographical characteristics. The vegetation diversity in this region has not been fully studied to monitor the changes that happen over time in these habitats. This study aims to identify the floristic diversity and vegetation structure of the plant species in invaded habitats of the western region of Saudi Arabia. A total of 58 stands in the different invaded habitats (i.e., mountains, protected areas "ridge mountain habitat", wadis, farmlands, ruderal areas, and coastal areas) were examined. A total of 146 plant species (94 native and 52 alien species) distributed among 132 genera and 49 families were recorded. Asteraceae, Poaceae, and Fabaceae were the most represented families and accounted for approximately 35% of the identified species. Multivariate analysis of the identified species clustered them into four main vegetation groups: VG I dominated by Opuntia ficus-indica-Juniperus phoenicea, VG II dominated by Reichardia tingitana-Heliotropium aegyptiacum, VG III dominated by Prosopis juliflora-Acacia seyal-Abutilon pannosum, and VG IV dominated by Suaeda monoica. The ecological information represented in this study may help in monitoring the changes in vegetation diversity across the western region of Saudi Arabia and designing the required conservation plans.